//===--- TypoCorrection.h - Typo correction ---------------------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
//  This file defines the interface for doing typo correction.
//
//===----------------------------------------------------------------------===//

#ifndef POLARPHP_SEMA_INTERNAL_TYPOCORRECTION_H
#define POLARPHP_SEMA_INTERNAL_TYPOCORRECTION_H

#include "polarphp/basic/LLVM.h"
#include "polarphp/ast/Identifier.h"
#include "polarphp/ast/DeclNameLoc.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/STLExtras.h"

namespace polar {

class LookupResult;
class TypeChecker;

/// A summary of how to fix a typo.  Note that this intentionally doesn't
/// carry a candidate declaration because we should be able to apply a typo
/// correction even if the corrected name resolves to an overload set.
class SyntacticTypoCorrection {
public:
   DeclName WrittenName;
   DeclNameLoc Loc;
   DeclName CorrectedName;

   SyntacticTypoCorrection(DeclName writtenName, DeclNameLoc writtenLoc,
                           DeclName correctedName)
      : WrittenName(writtenName), Loc(writtenLoc), CorrectedName(correctedName) {}

   void addFixits(InFlightDiagnostic &diagnostic) const;
};

/// A collection of typo-correction candidates.
class TypoCorrectionResults {
public:
   DeclName WrittenName;
   DeclNameLoc Loc;
   bool ClaimedCorrection = false;

   SmallVector<ValueDecl *, 4> Candidates;

   TypoCorrectionResults(DeclName writtenName, DeclNameLoc loc)
      : WrittenName(writtenName), Loc(loc) {}

   /// Try to claim a unique correction from this collection that's simple
   /// enough to include "inline" in the primary diagnostic.  Note that
   /// a single correction might still correspond to multiple candidates.
   ///
   /// The expected pattern is that CorrectedName will be added to the
   /// diagnostic (as in "did you mean <<CorrectedName>>"), and then addFixits
   /// will be called on the still-in-flight diagnostic.
   ///
   /// If this returns a correction, it flags that that's been done, and
   /// the notes subsequently emitted by noteAllCandidates will only make
   /// sense in the context of a diagnostic that suggests that the correction
   /// has happened.
   Optional<SyntacticTypoCorrection> claimUniqueCorrection();

   /// Emit a note for every candidate in the set.
   void noteAllCandidates() const;

   /// Add all the candidates to a lookup set.
   void addAllCandidatesToLookup(LookupResult &lookup) const;

   /// Look for a single candidate in this set that matches the given predicate.
   template <class Fn>
   ValueDecl *getUniqueCandidateMatching(Fn &&predicate) {
      ValueDecl *match = nullptr;

      for (auto candidate : Candidates) {
         // Ignore candidates that don't match the predicate.
         if (!predicate(candidate)) continue;

         // If we've already got a match, the match is no longer unique.
         if (match) return nullptr;

         // Record the still-unique match.
         match = candidate;
      }

      return match;
   }
};

} // end namespace polar

#endif // POLARPHP_SEMA_INTERNAL_TYPOCORRECTION_H
